The dielectric and thermal properties of Bi (bismuth)-layered perovskite SrBi2Ta2O9(SBT) are discussed in comparison with ferroelectric thin BaTiO3films. Although these two perovskites exhibit quite a different nature, the dielectric properties of BaTiO3thin film are similar to those in bulk SBT. The dielectric properties and pseudo-two-dimensional structure between SBT and thin film suggest that the bulk layered ferroelectric SBT is a good model of ultra-thin ferroelectric film with two perovskite layers, free from any misfit lattice strain with substrate and surface charge at the interface with electrodes. Based on the mechanism of ferroelectric phase transition of SBT, it seems plausible that the ferroelectric interaction is still prominent but shows a crossover from ferroelectric to antiferroelectric interaction in perovskite ultra-thin films along the tetragonal axis.
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